Sample Coil Test (Motor, Generator & Transformer)

[ElecEE8]

Hi All,
Anybody can advise me, what is the right timing to perform and witness sample coil test of the machines (motor, generator also transformer)? I mean to factory acceptance test (FAT).

 

[electricpete]

For global VPI on medium voltage machines (motors and generators), we require 2 extra coils vpi'd at the same time as the stator in a "mock" slot (to give same penetration). The coils can be hi-pot or surge tested to failure and cut open for inspection of resin penetration at several points (inside the slot, at the bends and knuckle) anytime after vpi and prior to accepting delivery of the machine.

If you are an EPRI member, check out their guide for sample stator coil inspection

https://www.epri.com/#/pages/product/3002003261/

I haven't heard a similar procedure for transformers. Certainly not oil filled paper insulation transformers which do not undergo vpi. Even for dry epoxy transformers, I don't think the winding construction lends itself to this apprpoach.


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(2B)+(2B)' ?

 

[edison123]

In our repair shop, we do FAT both during coils manufacture and on completed windings, depending on the contract we signed with the client. Most of them will accept just one final FAT prior to despatch.

Muthu

http://www.edison.co.in

 

[ElecEE8]

Thank you Pete and Muthu for your reply!